It’s been well over a year since the Costa Concordia ran aground off the small island of Giglio on Italy’s west coast, killing 32 passengers and crew.

The captain, Francesco Schettino, is accused of sailing the vessel into a large rock while showing off for people on shore.

While Schettino’s case winds through the courts, the wreck of the Concordia still lies on its side.

Marine recovery experts have devised a complicated plan to roll the enormous cruise ship upright and tow it from the rocky seabed. Originally, the wreck was supposed to have been removed in time for this summer’s tourist season. Now it may be December before the 114,000-tonne ship is refloated, nearly two years after the accident.

A video of the Concordia operation by the marine salvage operators Titan Salvage and Micoperi:

The salvage operation, step by step:

1. Stabilization

The first phase involves anchoring the wreck to prevent any slipping or sinking along the steep seabed. Four anchor blocks are fixed to the sea bottom between the centre of the wreck and the coast. A ‘false seabed’ is built with massive bags pumped with ‘eco-friendly’ cement. The bags will be removed after the ship is salvaged.

2. Support system

An elaborate underwater platform is built on top of the strengthened seabed, complete with deep pilings. This creates a stable base for the hull once the ship is righted. After the platform is built, 15 massive flotation compartments are welded to the side of the ship.

3. Righting the Concordia

Using a system of anchor cables and strandjacks, the Concordia is slowly rolled onto the underwater platform. Great care must be taken not to buckle the hull. Although fuel and sewage was pumped out of the vessel in the weeks after it grounded, the ship still contains rotting food, passenger belongings and other potential pollutants. Another 15 floatation compartments are welded to the starboard side.

4. Floating the vessel

Water is gradually pumped out of the compartments, nudging the wreck upwards until just 18 metres remain submerged. The Concordia is expected to be towed to Sicily, where it will be cut apart for scrap.

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